package com.qinghe.utils;

import java.util.Map;

import org.springframework.beans.factory.NoSuchBeanDefinitionException;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;

@SuppressWarnings({ "unchecked", "rawtypes" })
public class SpringContextHolder implements ApplicationContextAware {
	
	private static ApplicationContext context;

	/**
	 * 实现ApplicationContextAware接口的context注入函数, 将其存入静态变量.
	 */
	public void setApplicationContext(ApplicationContext applicationContext) {
		context = applicationContext;
	}

	/**
	 * 取得存储在静态变量中的ApplicationContext.
	 */
	public static ApplicationContext getApplicationContext() {
		checkApplicationContext();
		return context;
	}

	/**
	 * 从静态变量ApplicationContext中取得Bean, 自动转型为所赋值对象的类型.
	 */
	public static <T> T getBean(String name) {
		checkApplicationContext();
		return (T) context.getBean(name);
	}

	/**
	 * 从静态变量ApplicationContext中取得Bean, 自动转型为所赋值对象的类型. 如果有多个Bean符合Class, 取出第一个.
	 */
	public static <T> T getBean(Class<T> clazz) {
		checkApplicationContext();
		Map beanMaps = context.getBeansOfType(clazz);
		if (beanMaps != null && !beanMaps.isEmpty()) {
			return (T) beanMaps.values().iterator().next();
		} else {
			return null;
		}
	}

	private static void checkApplicationContext() {
		if (context == null) {
			throw new IllegalStateException("applicaitonContext未注入,请在applicationContext.xml中定义SpringContextHolder");
		}
	}

    public static boolean containsBean(String name) {
        return context.containsBean(name);
    }

    public static boolean isSingleton(String name) throws NoSuchBeanDefinitionException {
        return context.isSingleton(name);
    }

    public static Class<?> getType(String name) throws NoSuchBeanDefinitionException {
        return context.getType(name);
    }

    public static String[] getAliases(String name) throws NoSuchBeanDefinitionException {
        return context.getAliases(name);
    }
	
}
